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Detecting fluorescence via CW or pulsed LEDs

  1. Jun 11, 2016 #1
    Hello forums,

    in the context of a little DIY-project I am planning to build a rudimentary fluorometer, which is actually doing nothing but checking whether an amout of protein is fluorescing or not, and roughly measuring its intensity.

    A highpower LED is used to excite the protein to the fluorescent state, while a phototransistor (specially sensitive to the fluorescent spectrum) starts measuring a short time after the LED has been turned off.
    The live time of fluorescence is in the region of a few nano seconds. For example a nanosecond pulsed measurement should (tightly) be able to solve the problem. Do you know circuitries which can handle this measurement cycle?
  2. jcsd
  3. Jun 11, 2016 #2
    I know its difficult.

    For the continuous approach:
    How well can optical filters block light? What is the best possible attenuation (below 200dollars)?
  4. Jun 13, 2016 #3


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    Staff: Mentor

    Why is the time constant so short? What is the fluorescing material?
  5. Jun 13, 2016 #4
    One can distinguish between fast and slow decaying luminscence. The fastest kind of luminescence is fluorescence. There is also phosphorescence, which is more of an "exite, and wait until it decays", whereas fluorescence is more of a direct conversion of one wavelength to another.


    Fluorescence is always in the nanosecond region.
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